1. Field of the Invention
This invention relates generally to electrical ground rod driving devices, and more specifically to apparatus of improved construction so as to be capable of performing its intended use with a user thereof standing, at all times during said use, at local earth level adjacent said electrical ground rod, said apparatus being further intended to drive said electrical ground rod completely into the earth without resort to the use of sledges or hammers.
2. Description of the Prior Art
Ground rods for electrical service are usually required by construction codes and accepted practice to be at least ten feet (greater than 3.0 meters) in length, and driven substantially vertically into the earth for their entire length. It has often, heretofore, been common practice to provide a laborer with a ladder and a sledge hammer, the laborer ascending the ladder to a height sufficient to enable striking the top end of a vertically held electrical ground rod with the sledge hammer, the laborer descending the ladder appropriately as the electrical ground rod is driven into the earth so as to readily repeat striking the top end of the electrical ground rod with the sledge hammer. This approach, while usually employed for its simplicity and minimal tool requirements, is accompanied by significant risks in that the ladder may become unstable from variations in terrain level and softness of the earth. Also, it often arises that the sledge does not squarely strike the top end of the electrical ground rod, producing strain on the laborer to retain control of the sledge hammer during such glancing blows. Moreover, it is not unusual for the sledge hammer to be dropped during such a glancing blow, creating a hazard to other persons proximate to the situs of the electrical ground rod.
Several inventions are present in the prior art which provide apparatus useful in assisting in driving posts and rods. Such devices range from simple manually operable weights vertically drivable onto attachments coupled to the posts or rods, to adaptations of devices commonly known as pile drivers. As examples of simple mechanical devices, reference is made to U.S. Pat. Nos. 2,690,055; 2,693,086; 2,802,340, 2,998,087; 3,115,199; 4,448,264; and 4,971,479. More complex devices are illustrated by U.S. Pat. Nos. 3,073,571; 3,499,497; and 3,827,509.
In U.S. Pat. No. 2,690,055, issued 09/28/54 to LUNDGREN, et.al. for "Post Driving Device," an annular cylindrical element, having most of its mass at a lower end, is placed around the post. Using the external handles provided, the element is manually vertically raised and then brought forcefully downwardly against a bracket relocatably affixed to the post being driven. In U.S. Pat. No. 2,693,086, issued 11/02/54 to CARUTHERS, et.al. for "Ground Rod Driver," an elongated hollow tube is configured to fit around the rod. A lower weighted end of the rod slides over a threaded collet type attachment relocatably coupled to the ground rod. The tube impacts vertically downwardly upon a shoulder of the collet under manual manipulation of the elongated tube. The patent to TALLMAN, issued as U.S. Pat. No. 2,802,340 on 08/13/57 for "Ground Rod Driver," is almost identical to the device of CARUTHERS, et.al., with TALLMAN being one of the co-inventors of the earlier patent. U.S. Pat. No. 2,998,087, issued 08/29/61 to IDDINGS for "Fence Post Driver," also uses an elongated tube, this tube having a weighted closure at its upper end, which is manually vertically drawn downwardly so that the weight strikes the upper end of the post being driven. Earlike handles are provided for ease of use of this device.
In U.S. Pat. No. 3,115,199, issued 12/24/63 to LINABERY for "Post Driving Device," a short section of tubing, having a weighted plug at an upper end thereof, is provide with extended downwardly directed handles to enable manually drawing the tube downwardly onto the top of the post being driven. The extent of the handles allows the user to stand on the ground surface while using this device. However, the length of the handles appears to limit the depth to which the upper end of the rod may be driven. Another elongated tube device is described in U.S. Pat. No. 4,448,264, issued 05/15/84 to PEYTON for "Ground Rod Driving Pole." This device includes a number of spring-loaded pins passing transversely through the tube, each generally horizontally, in a spaced apart arrangement longitudinally along the extent of the tube. The pins are first retracted to ride along an exterior surface of a ground rod inserted into the tube, except for the uppermost pin. As the tube is manually raised and lowered, the upper transverse pin strikes the upper end of the ground rod until the raising of the tube between downward strokes enables the next lower transverse pin to pass over the upper end of the ground rod, this pin then becoming the driving impact pin. Each such transverse pin sequentially is allowed to pass over the top end of the ground rod.
For posts having pre-formed transverse holes, a relocatable bracket engaging a selected hole through the post is taught by BYERS, Sr., et.al. in U.S. Pat. No. 4,971,479, issued 11/20/90 for "Post Driver," to serve as an impact surface for an annular weight element drawn downwardly thereon. The weight may be placed below the bracket, before attachment of the bracket, to assist in removing the post.
A small version of a hydraulic pile driver is described in U.S. Pat. No. 3,073,571, issued 01/15/63 to WUNSCH for "Tractor Mounted Metal Post Driver." Pneumatic Jack hammers engage with brackets affixed to poles in both U.S. Pat. No. 3,499,497, issued 03/10/70 to MOORE for "Sign Pole Driver," and U.S. Pat. No. 3,827,509, issued 08/06/74 to LARSON for "Floating Type Drive Spike Accessory."